This review is just for the casino, not for the rooms. Mandalay Bay is one of the better-looking casinos on the strip. However, it's very different than many of the other casinos in that it's not even close to the gimmicky-ness that is proudly boasted by casinos such as Paris, The Venetian, Treasure Island, etc. Nice casino to gamble/eat/watch shows in, pretty relaxed atmosphere and not as crowded as some of the others since it's at one end of The Strip. I like that it doesn't smell like cigarette smoke on the floors either. Friendly staff.
If you want to visit the Shark Reef, plan in advance and don't wait for your last day in Vegas to do it, because lines can get incredibly long during prime tourist season and tickets have been sold out before.